Hi Kevin,
Whether your trauma was the start of your BFS or not, you sound like you do have BFS and not ALS. Have a read through the sticky post "BFS in a nutshell"
http://nextination.com/aboutbfs/forums/ ... .php?t=200 and remind yourself of the difference in the twitches.
Certainly many people have cited stress as their precursor to BFS, whether that was the cause or the side effect that made it visible is another matter, but trauma and stress obviously go hand in hand.
Do yourself a BIG favour and quit doing the self diagnosis and internet research before you drive yourself to despair. If you really are worried go and see your doctor and speak to him about it and put your mind at ease, and certainly stop getting ideas that certain things increase your risk of developing the nasty disease, you really will drive yourself mad!
I'm sure you are fine. Sorry to hear about the shoulder.